Multistage dielectrophoretic separation of various kinds of biological microparticles with quadrupole microelectrode capillary

在平面四极微电极(工作区域半径为50μm或65μm)上，用荧光显微镜测量了单个微粒(半径为0.35~7.3μm)和DNA(4 0kBP)的介电。在四极微电极上施加频率为1 kHz~10 MHz、电压为0~5V的交流电。采用聚苯乙烯、聚苯二甲酸酯、碳微球和酵母细胞作为样品微球。定量分析了单个微粒和单个DNA的本征电导率、表面电导率、介电常数、尺寸以及水介质的电导率和介电常数。利用自制的毛细管四极微电极(工作半径82.5μm，长2.35 cm)，结合场流分离技术，实现了微粒间的分离。

Dielectrophoresis of single microparticles (0.35 - 7.3 μm in radius) and DNA (40 kbp) were measured in a planar quadrupole microelectrode (50 μm or 65 μm in working area radius) with a fluorescence microscope. An alternating current (ac) of 1 kHz - 10 MHz in frequency and 0 - 5 V in voltage was applied to the quadrupole microelectrode. Polystyrene, polystyrene-carboxylate and carbon microparticles, and yeast cell were adopted as a sample microparticle. The dielectrophoretic mobilities of the single microparticles and single DNA were analyzed quantitatively with their intrinsic and surface conductivities, their permittivity, and their size as well as the conductivity and permittivity of aqueous media. Some separations among the microparticles were demonstrated with a fabricated capillary quadrupole microelectrode (82.5 μm in radius of working area, 2.35 cm in length) by combining the technique of field flow fractionation.